The lightbulb went off the day I realized that while recycling is great, if someone is able to reuse the stuff you no longer want, like your old sofa, you're keeping not just a 100-lb. sofa out of a landfill but also 20 to 40 times that in the raw materials needed to make a new sofa.

This was back in 2003, when I was working with a nonprofit in Arizona to secure transitional employment for homeless men. One job involved helping businesses in downtown Tucson recycle. Our workers would drive around, collecting recycling and interacting with shop owners, and in...